The above quote is what Trump said. What I have read to date is that it will take up to ten years to replace Chinese rare earths.
Any country who has rare earths can increase production. But production is only half the story. The rare earth need to be processed and refined
The “processing” is not hard but “refining” to obtain the levels of refinement needed for high tech industry is not easy at all. It requires specialized knowledge, equipment and a specialized supply chain. China has that, no one else does. It takes about ten years to develop those capabilities - or at least so I am told.
If that is correct, then Trump’s statement quoted above is typical Trump hyperbole and blather.